This invention is directed to a preformed, shaped oriented copolyetherester elastomeric belt having straight sides that functions as a spring and is capable of absorbing energy when used in a torque converter.
Various types of couplings to connect an input shaft to an output shaft to supply power from a prime mover to a load are known. Frequently, the shafts are "locked" together in a manner such that torsional vibrations or shocks on either the input or output shaft are transmitted to the other shaft, many times with amplification, as well as to other parts of the apparatus. These vibrations, or shocks, may be caused by power surges, misfires and from sudden changes in demand load.
In the acceleration and deceleration of a given load, for example, short-term discontinuities of the energy flow, including reverse direction flow, may occur and this may result in such objectionable conditions as bumps or jerks or even cause harm to the equipment or stalling of the prime mover. This is particularly true in systems where a constantly or already running prime mover picks up a load when a clutch in the power train is actuated. Turning on an automobile air conditioner, for example, clutches in a heavy load, the compressor, in an already running power train which may be at a great variety of power conditions. Similarly, "locking up" the torque converter of an automatic transmission when cruising conditions are attained is a situation where load and input may be momentarily mismatched depending on the amount of hydraulic slip at the instant of engagement. In all of these systems, and others, troublesome vibrations or shocks may occur and with them inherent problems in the operation of such systems.
It is desirable to provide locked-up shafts with a cushioning device so that torsional vibrations or shocks are largely absorbed and not substantially transmitted from one shaft to the other. For example, in automotive vehicles that make use of an automatic transmission it may be desirable to include a lock-up clutch to couple the engine drive shaft directly to the transmission input shaft when the vehicle reaches a certain speed. Its purpose is to eliminate fuel losses related to torque converter slip. Shocks ordinarily occur during lock-up. Further, if the shafts are rigidly locked by this clutch, torsional vibrations or shocks on either shaft are transmitted to the other, as well as to the rest of the vehicle and its occupants. A torque cushioning device in series with the clutch is therefore desirable. Such a torque cushion must handle full engine torque, and any fractional part thereof, plus or minus the torsional vibrations derived from cyclic engine firing and other changes in demand load by the wheels. The softer the cushion, the lower will be its natural frequency, and the better it will be for shock and vibration damping.
It, therefore, has become standard practice to incorporate some form of cushioning coupling in shaft lock-up systems to take up the initial load and to damp out bumps in operation. Metal compression springs have been used for the torque cushioning portion of a torque converter, such as a lock-up clutch in an automotive vehicle, but their very presence, i.e, the space they occupy, plus their necessary loading elements, severely limits the amount of differential rotation permitted between the two shafts. Such systems are hard cushions with correspondingly high natural frequencies of vibration and, therefore, they perform poorly in response to sudden power surges and do little toward the damping of external vibrations. At certain speed conditions a noticeably jerky motion occurs.